You probably vaguely recall learning in chemistry that everything shrinks when it gets cold. Everything except water. Water is weird. When water freezes, it expands. There’s not enough space here to tell you why freezing water expands but you can blame its molecular structure.
If a puddle freezes and expands, that’s fine and dandy – at least until you slip on it. If your water supply lines freeze and expand, that’s definitely not fine and dandy – frozen pipes rupture and crack.
If you have a home which you expect to be vacant or unsupervised for any period of time, winterization is imperative. Winterization is the process of removing water from the home’s piping by draining the home’s pipe systems and introducing anti-freeze agents to prevent any remaining water from freezing.
Five Easy Steps to Winterization
1. Turn off heat sources to furnace and water heater.
Furnace can be turned off by flipping the power switch. The same approach applies to electric or oil water heaters. For gas water heaters, turn off the gas valve.
2. Close main water valve.
After turning off the valve, open all inside faucets and all outside faucets to drain all water from the pipes inside and outside the home. Don’t forget to remove and store garden hoses.
3. Drain water heater.
Connect a hose to the drain at the bottom of the heater and let it run into the floor drain. If there’s no drain, extend the hose to the outside or establish a "bucket brigade" to a nearby laundry tub. After draining the water heater, close the drain valve. If the home has a hot water heating system (baseboard or conventional radiators), the system also must be drained.
4. Flush, dry and treat toilets and traps.
Flush each toilet, then open the tank and sponge away remaining water. Dip out any remaining water, then add diluted non-toxic propylene glycol anti-freeze. Some water must remain in the toilet bowl to seal traps, which prevent sewer gas from entering the home through the drain system. When finished with toilets, pour non-toxic solution into all drains – basins, sinks, laundry tubs, bath tubs, and showers.
5. Protect exposed pipes.
Wrap exposed pipes with insulation or, in cases in which water cannot be totally removed from pipes that are exposed, apply heat tape.
In cases in which the home will be unoccupied for a relatively short period, such as a vacation, we recommend that the property be supervised to prevent any surprises. Ask a friend to visit daily to check power and heating system to help ensure that the pipes won’t freeze. The person monitoring the home should have access to utility and service company contact information in case of emergency.